Ordering the apprentice plant mechanic to spend the same period on licence and banning him from driving for four years, Judge Lynch told Devlin that the fact that he had his eyes off the road to use his mobile was “particularly egregious.”

“This case emphasises, if any emphasis were needed, of the dangers inherent in using mobile devices whilst driving, whether that be making calls, accepting calls or as in this particularly egregious example, actually browsing the Internet at the relevant time,” declared the judge.

In what is believed to be the first case in Northern Ireland of a driver using an app when a road traffic collision was caused, Devlin pleaded guilty to causing the death of Ian Leonard Bailie by driving dangerously on the Old Ballynahinch Road in Lisburn on October 28, 2014.

The court heard at an earlier hearing last week, and repeated by Judge Lynch on Tuesday, how a Skoda Octavia car was waiting to overtake a tractor and slurry tanker when Devlin, driving a works VW Caddy van, mounted the grass verge to avoid a collision with the car but instead, struck a telegraph pole.

Unfortunately Mr Bailie, the court heard, had been standing at his gateway on the other side of the BT pole and it struck him.

He was taken to the Royal Victoria Hospital for treatment, but tragically, almost a month later, on November 19, “he succumbed to his injuries.”

Returning to the scene of the impact, the judge said Devlin “jumped out of the van” and told the driver of the Octavia that he was “sorry” but that he mounted the grass verge to avoid hurting her because he “saw there was children in the back.”

Forensic engineer Mr Calendar examined the scene and from his report, it appeared “this was a relatively straight portion of road” to such an extent that Devlin would have had sight of the Octavia and tractor for around 300 metres and for just over 13 seconds as he approached the scene. The court heard there was no evidence of excess speed due to a GPRS device installed on the van which belonged to WAC McCandless.

What did transpire however when Devlin’s mobile phone was examined, was that it had been used to send a text message and for “web browsing” during the course of his journey.

During his initial police interview Devlin denied using the phone but during the second when the phone evidence was put to him, admitted he had sent a text as he left Belfast in slow moving traffic.

He further confessed that up until the time of the collision, he had been browsing Gumtree “to look at lists of cars,” stating that as his phone locked and required a passcode after a certain amount of time, he had left it on the passenger seat and “admitted to keeping the phone open.”

“The explanation for this catastrophic mistake is simple,” Judge Lynch told the court, “the phone had been in continuous use prior to the accident itself.”

He said the fact the mobile phone had been used “over a protracted period” was a “particularly serious aspect of this case as were his two previous convictions for careless driving committed within a week of each other in March 2013.

The judge revealed that in those offences, Devlin had “driven to the right of a keep left sign and drove over the brow of a hill at high speed in the middle of the road.”

“Anyone would have thought this would have been a warning to you to take more care,” the judge told Devlin.

Turning to the consequences of his 13 seconds of inattention, Judge Lynch said the devastation was “graphically demonstrated” in the victim impact statement of Mrs Carol Bailie who said her husband had been “looking forward to, and entitled to look forward after a life time of work, to contented retirement - that’s been totally destroyed.”

Mrs Bailie, said the judge, was Devlin’s second victim as her life “has been blighted by what is an irreparable loss,” outlining that as well as the loss of her husband and life partner, she has become isolated, doesn’t feel able to socialise the way she did and doesn’t sleep properly.

In mitigation, the judge said he accepted Devlin had expressed “genuine remorse” for what he had caused and had even wanted to attend his victim’s wake “but was advised against that by the police.”

Concluding his sentencing remarks, Judge Lynch said as a result of Devlin failing to see “what was obviously in front of you... a man looking forward to retirement is now dead and he can never be replaced.”

“Nothing I can say and no sentence I can pass will be a substitute for the tragedy that’s been occasioned to Mrs Bailie,” said the judge who told Devlin that he would have faced a longer term in jail if he hadn’t pleaded guilty.

As the judge announced the 27 month sentence, half to be served in custody and half on licence, Devlin looked shocked and was visibly shaking as he was led from the dock in handcuffs.

Outside the court, neither his family nor Mrs Bailie wished to comment.